1. The Field of the Invention
The present invention relates to systems and methods for processing electronic documents. More particularly, the present invention relates to electronic documents having embedded digital signatures and to systems and methods for processing electronic documents such that the embedded digital signatures are validated.
2. Background and Related Art
Signatures are often a formal requirement of various transactions. Many legal instruments, such as wills, contracts, and deeds, are not legally enforceable unless they are signed by the appropriate persons in a specified way. While the specific legal requirements relating to signatures may vary across jurisdictions, the requirement of having a signature on a document serves fundamental purposes. For instance, signatures should be indicative of the person that signed a particular document and signatures should be difficult to reproduce without authorization. Signatures should also identify what is signed such that it is difficult to alter the signed matter without being discovered. Signatures further serve to authenticate a document by identifying each person that signed the document and the act of signing a document is intended to bring the legal aspects of signing the document to the attention of the signer.
The procedures for affixing signatures to paper documents is relatively well established. In the digital realm, however, persons are more reluctant to affix a digital signature to an electronic document for various reasons even though the characteristics of digital signatures (such as authenticity and security) are arguably better than their paper counterparts. For example, persons place more trust in paper signatures in comparison to digital signatures.
When a digital signature is employed to sign a document, the signer first identifies exactly what is being signed. The document or data identified by the signer is hashed to generate a hash result that is essentially unique to the document. Then, the hash result is converted into a digital signature using a private key of the signer to encrypt the hash result. In this manner, both the document and the private key are related to the digital signature.
A significant disadvantage of digital signatures is that they are not an integral part of the document but are attached as a separate file to the document. This creates a significant risk that the digital signature will become disassociated from the document and nullify the effect of the digital signature and results in a document that is not verifiable, especially when the document and the attached digital signature are either stored or transmitted.
Often, documents that are signed with digital signatures are validated or verified. Verifying a digital signature requires that the verifier have access to the public key of the signer in order to decrypt the hash result that was encrypted with the private key of the signer. The difficulty of this proposition is that the public and private key of the signer are not intrinsically associated with the signer. In most cases, a certificate authority (CA) is used to solve this problem. The CA is a trusted third party that issues a digital certificate that states that the signer identified in the digital certificate is the owner of the public key that is the subject of the digital certificate.
Even though the CA provides some assurance that the proper key pair is being employed, digital signatures are still attached as a separate file to the documents that they digitally sign. As previously stated, this weakens the digital signature as an authenticator because the attachment can become separated from the document. This problem can become even more complicated when a document is signed by multiple persons. In this case, subsequent signatures do not incorporate previous signatures because each signature is a separate attachment. The ambiguity and uncertainty surrounding electronic documents is partially responsible for the reluctance to process electronic documents without a paper copy. What is needed are systems and methods that allow electronic documents that are digitally signed to be validated, processed and/or recorded.
The present invention addresses these and other problems by providing systems and methods for digitally signing and verifying electronic documents by embedding the digital signatures in the electronic document. An extensible markup language (XML) schema is provided and is used to embed digital signatures in the electronic documents. The XML schema provides elements and tags that are used to store each digital signature that will become part of the electronic document. XHTML is used along with the XML schema such that the electronic document can be read and processed by both users and computers.
When an electronic document is created, either from a template or as a new document, a signature block is included for each person that will digitally sign the document. The allotted signature blocks may include notary signature blocks, recorder signature blocks, and other signature blocks as needed. Alternatively, each signature block is generated as necessary and appended to the document as the document is digitally signed. Thus a signature block for a notary is not added to the electronic document until the electronic document has been digitally signed by the primary signers. Similarly, a signature block for the recorder is not added to the electronic document until the electronic document has been digitally signed by the notary.
In one example, the signature block includes a reconstruct attribute that is used when the electronic document is validated or verified. The reconstruct attribute helps to reconstruct the document to a previous state by helping identify information or data that should be removed or stripped from the electronic document. Once the document has been reconstructed, it is hashed to generate a hash value that is compared to a decrypted value of the digital signature of the signer being validated. If these values match, then the digital signature and the document are validated. Because the digital signatures are embedded in the electronic document, they cannot become disassociated from the digital document.
In another example, the signature blocks do not have a reconstruct attribute, but can be reconstructed based in part on the identity of the signer. For example, a notary usually digitally signs an electronic document after the primary signers have digitally signed the document. Thus, reconstructing the document to verify the primary signers requires that the notary signature block and/or digital signature be stripped or removed from the document.
The electronic documents can be processed when they are received by reconstructing the electronic document to a previous state. In the case of electronic documents being recorded, the content of the electronic document as digitally signed by the notary public digital is usually verified. If verification is successful, the recorder is able to insert endorsement data into the digital document and record the electronic document. Finally, the recorder digitally signs the electronic document using a recorder signature block that was already provided in the electronic document and generates a receipt that is also digitally signed by the recorder. In addition, the recorded electronic document and the digitally signed receipt are returned to the originator that is identified in routing information that was included in the electronic document.
Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by the practice of the invention. The features and advantages of the invention may be realized and obtained by means of the instruments and combinations particularly pointed out in the appended claims. These and other features of the present invention will become more fully apparent from the following description and appended claims, or may be learned by the practice of the invention as set forth hereinafter.